Background
It is known that proprioception is necessary for the control of human movement [
1]. Proprioception is described as the joint’s sensation, position, and movement; also, the sense of force, effort, weight, and perceived timing associated with muscular contraction [
2]. Proprioceptive inputs are derived from afferent information received from muscle, joint, and skin receptors [
2]. These receptors have different roles depending on the range at a given joint; for example, previous studies have found that joint receptors to be activated near the end of the joint range, while muscle spindles provide afferent inputs throughout the physiologic ranges [
3].
It is challenging to measure proprioception because of its complex function. In previous studies, proprioception has been measured by force–plate analysis [
4], electromyographic (EMG) activity [
5], and position sense [
6]. Position sense is defined as the ability to perceive the movement or orientation of a body segment in space. Some studies have used repositioning error (RE) or position sense to measure proprioception in joints [
6,
7]. There is evidence that individuals with chronic low back pain (CLBP) have reduced proprioceptive ability and larger lumbar RE in the lumbar region [
7,
8], but some studies have found no significant difference between subjects with CLBP with pain-free participants [
9,
10]. If proprioceptive deficits exist, rehabilitation programs should be designed to improve proprioception; however, there has been little research to support this.
In recent years, the use of a therapeutic tool called kinesiology tape (KT) has increasingly become popular to use for musculoskeletal disorders. KT is made up of colorful elastic cotton strips with an acrylic adhesive that may be stretched to up to 140% of their original length [
11]. KT is assumed to have several benefits [
12], including (1) pain reduction through neurological suppression, (2) reposition of subluxated joints by decreasing abnormal muscle tone, (3) to create more space by lifting fascia and soft tissue to improve circulation, (4) correcting muscle function by strengthening weak muscles (5) and providing sensory stimulation to improve proprioception [
12,
13].
The compressive and stretching effect of KT provides additional cutaneous stimulations, and these stimulations transfer more information regarding the joint position and movement to the central nervous system (CNS) for integration resulting in increased proprioception [
2,
14]. However, there have been controversial results regarding the effect of KT on proprioception.
Some studies have shown improved proprioception through augmented cutaneous sensory stimulations provided by KT [
14,
15], whereas others have found no changes in proprioception using KT [
13,
16]. Therefore, CLBP individuals with poor proprioception might benefit from the application of KT.
As yet, there is a lack of research exploring the effect of KT on lumbar proprioception. The purpose of the present study was to explore the short-term effect of KT on lumbar proprioception, pain, and functional disability in individuals with nonspecific CLBP. The associations between pain intensity, disability, and lumbar RE were also evaluated in these individuals. It was hypothesized that applying KT on the lumbar spine would improve lumbar proprioception, pain, and disability compared to the placebo group in individuals with nonspecific CLBP.
Discussion
The current study aimed to examine the effect of KT application on lumbar proprioception, pain, and functional disability in individuals with nonspecific CLBP. The results showed that pain (Total score (S/A), VAS and PPI) and disability scores significantly improved after 3 days of taping in the KT group with large effect sizes, but no significant differences in RE (AE or CE) were found in any of the three angles (45° and 60° flexion and 15° extension). In the placebo group, only PPI was significantly reduced after 3 days of placebo taping without tension. Also, only the total score of pain (S/A) showed significant differences between the groups with a large effect size.
Participants in the KT group had mild to moderate pain levels and showed approximately 23% reduction of pain over 3 days; therefore, possibly over a longer period, a greater reduction would have been achieved. However, KT is typically worn for 3–5 days.
There are several studies investigated the effect of KT on pain and disability in individuals with LBP [
17,
30,
31]; however, there is a large variability in a combination of KT with other therapies, such as exercise program, manual therapy, and traditional physical therapy. Some studies compared the effect of KT to placebo taping on pain and disability. In line with our findings, some studies showed that the levels of pain and disability significantly decreased after taping [
18,
32‐
34], and some reported that KT is better than placebo taping in patients with CLBP [
32,
34,
35]. On the other hand, some studies found no significant decrease in pain or disability after the intervention [
36,
37], and that the application of KT was not better than placebo taping for patients with CLBP [
31,
33,
37], which is contradicted with our findings. In the current study, similar to previous studies [
18,
32,
33,
35,
36], the placebo taping had therapeutic effectiveness beyond the placebo. It seems that applying placebo taping without tension even with one strip can create some physiological.In the current study, KT only reduced the total score of pain (S/A) in the KT group compared to the placebo group. It indicates that KT can affect other aspects of pain (i.e., sensory, affective) that placebo taping could not affect. Because of the PPI reduction in the placebo group, it seems that the application of placebo taping could reduce pain intensity due to a placebo effect in the patients with CLBP. Based on our results, both KT and placebo taping can reduce pain in patients with CLBP, but the effects of KT are higher than placebo taping.
Some physiological mechanisms of KT effects have been proposed. Pain reduction after applying KT with tension may be due to lifting the skin and enhancing subcutaneous space and, as a result, reduced activation of pain receptors, also possibly activates descending inhibitory system. Also, in the gate control theory of pain, tactile stimulation of KT would reduce the afferent signal of large-diameter non-nociceptive fibers resulting in a reduction of pain [
18,
38,
39]. In addition, some positive effects of KT may indirectly affect pain and disability improvement, such as normalize muscle tone, improvements of postural control, range of motion, circulation, and proprioception [
40‐
43].
The previous studies never evaluated the effects of KT on pain using SF-MPQ as a multidimensional tool in individuals with nonspecific CLBP, and they measured pain by VAS [
18,
32,
34] or NRS [
33,
35‐
37]. The current study is the first to assess the effects of KT on pain using SF-MPQ in individuals with nonspecific CLBP.
Also, there were no significant differences (between-group or within-group) for lumbar RE (AE and CE) in the angles (45° and 60° flexion and 15° extension). To the best of our knowledge, this is the first study to evaluate the effect of KT on lumbar proprioception in patients with LBP. Several studies have evaluated the effect of KT on proprioception in peripheral joints, especially knee and ankle in injured or non-injured individuals [
11,
13‐
15] that are conflicting with our results. Several explanations may explain our results. Based on our results, it seems that placebo taping may affect and reduce pain, albeit slightly. Therefore, the lack of non-taping group and the effect of placebo taping may have affected the results of between-group comparison in this study.
A systematic review reported that patients with LBP have impaired lumbar proprioception compared with controls when measured actively in sitting positions [
4]. In our study, lumbar proprioception was actively measured in standing positions that may have affected the results. Also, various methods of measuring lumbar proprioception exist, including joint RE, the threshold to detection of passive motion, and directional motion perception [
4]. In the current study, lumbar proprioception was measured by repositioning error. However, the best method of measuring proprioception is still unclear. In addition, in the previous studies, target positions for repositioning ranged from neutral lumbar spinal posture to target angles in pelvic tilting and lumbar flexion, extension, lateral flexion, and rotation in patients with LBP [
4,
6,
7]. This study reproduced two different trunk positions from neutral to 45° and 60° flexion and one position from neutral to 15°extension. Perhaps within other ranges, individuals show more proprioception deficits and/or improvements after KT.
The potential mechanism by which KT improves proprioception is not yet understood. Some authors have hypothesized that cutaneous feedback supplied by KT could be increased. Applied pressure and stretching due to KT application on the skin at extremes of motion, similar to joint mechanoreceptors, can also stimulate cutaneous mechanoreceptors and signal information of joint movement or joint position [
13,
14,
44]. Konishi et al. (2013) confirmed that KT could counter quadriceps femoris weakness due to attenuated la afferent activity [
44].
It seems that tactile stimulation of KT was not enough for improvements of proprioception may be due to short-term assessment or method of taping in our study. There are direct relationships between impaired proprioception, pain, and reduced quality of life [
45]. In the current study, pain and disability improved in the patients; therefore, there would be improvements in proprioception as well as pain and disability reduction in the KT group.
It has been proposed that proprioceptive deficits may lead to trunk muscle dysfunction also may cause alterations in normal afferent inputs from the affected muscles. In neutral posture, muscle afferents could be considered as primary contributors to position sense because ligaments are under minimal tension [
3,
5]. In contrast, previous studies reported that KT could normalize lumbar muscle function and postural control in patients with LBP [
17,
41,
43], and it is thus expected to improve lumbar proprioception.
The tension of KT is described as one of the critical factors for successful implementation. Theoretically, both 75 and 100% of tension are used to support weak muscle or correction of joint position, 25–50% for muscle activation in weak muscles positioned from the origin to the muscle insertion, 15–25% for muscle inhibition caused by overuse or muscle overstretching placed from the insertion towards the muscle origin, and 0–15% for reduction of edema [
12]. The best tension of KT to improve proprioception is not evident yet. In the current study, we used the star shape of KT with 15–25% tension because it was reported that the star shape of KT with 15–25% tension significantly improved pain, disability, trunk muscle endurance, and trunk flexion range of motion in patients with nonspecific CLBP [
4]. A different method of KT with different tension may enhance lumbar proprioception in patients with CLBP.
Besides, the moderate positive correlation between CE of 15° extension and disability in these patients indicates that those with higher disability display a greater RE. Previous research suggests that spinal RE is the largest among individuals with higher disabilities. Also, there is a positive correlation between functional disability and RE [
6,
9]. Those with a higher functional disability may have greater overall disruption of the pain neuromatrix within the CNS [
6]. The reasons for nonsignificant correlations between functional disability, pain, and both CE and AE at other angles are unclear. Motor control impairments in spinal posture and movement, as well as trunk muscle activation, have been reported among patients with nonspecific CLBP [
6,
43]. Thus, these changes may explain significant or nonsignificant correlations between functional disability, pain, and both CE and AE in the three measured angles, since RE is influenced by muscle spindle feedback [
7] and spinal posture [
6].
Limitations
In the current study, some limitations should be considered while interpreting the findings. First, we compared the effects of KT with a placebo group, but the placebo taping was not a real placebo due to the volume of tape used, which should be thinner than KT with less stimulation of subcutaneous afferent sensory fibers. Also, the lack of a non-taping group is another limitation of the current study. Moreover, we only examined the short-term effects of star shape taping with 15–25% tension; however, higher tensions may have different effects on lumbar RE. Therefore, future studies should compare different methods of taping with non-taping, also assess longer follow-ups in patients with CLBP.
Clinical implication
The use of KT would be beneficial to decrease the level of pain and disability in individuals with nonspecific CLBP. Also, taping without tension even with one strip, such as placebo taping, may reduce pain in these patients. Since the placebo treatments are important tools that can be used by the medical community to complement regular therapies, the use of placebo taping can be helpful. Considering lumbar RE may assist therapists in identifying poor posture awareness and proprioception impairments among these patients.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.